Having a problem with this simple question

1. The problem statement, all variables and given/known data
I am trying to calculate a percent of error in a conservation of energy lab, and for some reason I am completely drawing a blank.
Just so you know what I am looking at,
I have about 10 values or so in 3 columns labeled KE, PE, E. E is KE + PE

2. Relevant equations

I wrote down (Elast - E1st)/ (Etotal) and then multiply by 100. Something just seems wrong here and I don't know why. Is that correct?

3. The attempt at a solution1. The problem statement, all variables and given/known data